user-manual: clean up fast-forward and dangling-objects sections
[git] / diff-lib.c
1 /*
2  * Copyright (C) 2005 Junio C Hamano
3  */
4 #include "cache.h"
5 #include "quote.h"
6 #include "commit.h"
7 #include "diff.h"
8 #include "diffcore.h"
9 #include "revision.h"
10 #include "cache-tree.h"
11 #include "path-list.h"
12
13 /*
14  * diff-files
15  */
16
17 static int read_directory(const char *path, struct path_list *list)
18 {
19         DIR *dir;
20         struct dirent *e;
21
22         if (!(dir = opendir(path)))
23                 return error("Could not open directory %s", path);
24
25         while ((e = readdir(dir)))
26                 if (strcmp(".", e->d_name) && strcmp("..", e->d_name))
27                         path_list_insert(xstrdup(e->d_name), list);
28
29         closedir(dir);
30         return 0;
31 }
32
33 static int get_mode(const char *path, int *mode)
34 {
35         struct stat st;
36
37         if (!path || !strcmp(path, "/dev/null"))
38                 *mode = 0;
39         else if (!strcmp(path, "-"))
40                 *mode = ntohl(create_ce_mode(0666));
41         else if (stat(path, &st))
42                 return error("Could not access '%s'", path);
43         else
44                 *mode = st.st_mode;
45         return 0;
46 }
47
48 static int queue_diff(struct diff_options *o,
49                 const char *name1, const char *name2)
50 {
51         int mode1 = 0, mode2 = 0;
52
53         if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
54                 return -1;
55
56         if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2))
57                 return error("file/directory conflict: %s, %s", name1, name2);
58
59         if (S_ISDIR(mode1) || S_ISDIR(mode2)) {
60                 char buffer1[PATH_MAX], buffer2[PATH_MAX];
61                 struct path_list p1 = {NULL, 0, 0, 1}, p2 = {NULL, 0, 0, 1};
62                 int len1 = 0, len2 = 0, i1, i2, ret = 0;
63
64                 if (name1 && read_directory(name1, &p1))
65                         return -1;
66                 if (name2 && read_directory(name2, &p2)) {
67                         path_list_clear(&p1, 0);
68                         return -1;
69                 }
70
71                 if (name1) {
72                         len1 = strlen(name1);
73                         if (len1 > 0 && name1[len1 - 1] == '/')
74                                 len1--;
75                         memcpy(buffer1, name1, len1);
76                         buffer1[len1++] = '/';
77                 }
78
79                 if (name2) {
80                         len2 = strlen(name2);
81                         if (len2 > 0 && name2[len2 - 1] == '/')
82                                 len2--;
83                         memcpy(buffer2, name2, len2);
84                         buffer2[len2++] = '/';
85                 }
86
87                 for (i1 = i2 = 0; !ret && (i1 < p1.nr || i2 < p2.nr); ) {
88                         const char *n1, *n2;
89                         int comp;
90
91                         if (i1 == p1.nr)
92                                 comp = 1;
93                         else if (i2 == p2.nr)
94                                 comp = -1;
95                         else
96                                 comp = strcmp(p1.items[i1].path,
97                                         p2.items[i2].path);
98
99                         if (comp > 0)
100                                 n1 = NULL;
101                         else {
102                                 n1 = buffer1;
103                                 strncpy(buffer1 + len1, p1.items[i1++].path,
104                                                 PATH_MAX - len1);
105                         }
106
107                         if (comp < 0)
108                                 n2 = NULL;
109                         else {
110                                 n2 = buffer2;
111                                 strncpy(buffer2 + len2, p2.items[i2++].path,
112                                                 PATH_MAX - len2);
113                         }
114
115                         ret = queue_diff(o, n1, n2);
116                 }
117                 path_list_clear(&p1, 0);
118                 path_list_clear(&p2, 0);
119
120                 return ret;
121         } else {
122                 struct diff_filespec *d1, *d2;
123
124                 if (o->reverse_diff) {
125                         unsigned tmp;
126                         const char *tmp_c;
127                         tmp = mode1; mode1 = mode2; mode2 = tmp;
128                         tmp_c = name1; name1 = name2; name2 = tmp_c;
129                 }
130
131                 if (!name1)
132                         name1 = "/dev/null";
133                 if (!name2)
134                         name2 = "/dev/null";
135                 d1 = alloc_filespec(name1);
136                 d2 = alloc_filespec(name2);
137                 fill_filespec(d1, null_sha1, mode1);
138                 fill_filespec(d2, null_sha1, mode2);
139
140                 diff_queue(&diff_queued_diff, d1, d2);
141                 return 0;
142         }
143 }
144
145 /*
146  * Does the path name a blob in the working tree, or a directory
147  * in the working tree?
148  */
149 static int is_in_index(const char *path)
150 {
151         int len, pos;
152         struct cache_entry *ce;
153
154         len = strlen(path);
155         while (path[len-1] == '/')
156                 len--;
157         if (!len)
158                 return 1; /* "." */
159         pos = cache_name_pos(path, len);
160         if (0 <= pos)
161                 return 1;
162         pos = -1 - pos;
163         while (pos < active_nr) {
164                 ce = active_cache[pos++];
165                 if (ce_namelen(ce) <= len ||
166                     strncmp(ce->name, path, len) ||
167                     (ce->name[len] > '/'))
168                         break; /* path cannot be a prefix */
169                 if (ce->name[len] == '/')
170                         return 1;
171         }
172         return 0;
173 }
174
175 static int handle_diff_files_args(struct rev_info *revs,
176                 int argc, const char **argv, int *silent)
177 {
178         *silent = 0;
179
180         /* revs->max_count == -2 means --no-index */
181         while (1 < argc && argv[1][0] == '-') {
182                 if (!strcmp(argv[1], "--base"))
183                         revs->max_count = 1;
184                 else if (!strcmp(argv[1], "--ours"))
185                         revs->max_count = 2;
186                 else if (!strcmp(argv[1], "--theirs"))
187                         revs->max_count = 3;
188                 else if (!strcmp(argv[1], "-n") ||
189                                 !strcmp(argv[1], "--no-index")) {
190                         revs->max_count = -2;
191                         revs->diffopt.exit_with_status = 1;
192                 }
193                 else if (!strcmp(argv[1], "-q"))
194                         *silent = 1;
195                 else
196                         return error("invalid option: %s", argv[1]);
197                 argv++; argc--;
198         }
199
200         if (revs->max_count == -1 && revs->diffopt.nr_paths == 2) {
201                 /*
202                  * If two files are specified, and at least one is untracked,
203                  * default to no-index.
204                  */
205                 read_cache();
206                 if (!is_in_index(revs->diffopt.paths[0]) ||
207                                         !is_in_index(revs->diffopt.paths[1]))
208                         revs->max_count = -2;
209         }
210
211         /*
212          * Make sure there are NO revision (i.e. pending object) parameter,
213          * rev.max_count is reasonable (0 <= n <= 3),
214          * there is no other revision filtering parameters.
215          */
216         if (revs->pending.nr || revs->max_count > 3 ||
217             revs->min_age != -1 || revs->max_age != -1)
218                 return error("no revision allowed with diff-files");
219
220         if (revs->max_count == -1 &&
221             (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
222                 revs->combine_merges = revs->dense_combined_merges = 1;
223
224         return 0;
225 }
226
227 static int is_outside_repo(const char *path, int nongit, const char *prefix)
228 {
229         int i;
230         if (nongit || !strcmp(path, "-") || path[0] == '/')
231                 return 1;
232         if (prefixcmp(path, "../"))
233                 return 0;
234         if (!prefix)
235                 return 1;
236         for (i = strlen(prefix); !prefixcmp(path, "../"); ) {
237                 while (i > 0 && prefix[i - 1] != '/')
238                         i--;
239                 if (--i < 0)
240                         return 1;
241                 path += 3;
242         }
243         return 0;
244 }
245
246 int setup_diff_no_index(struct rev_info *revs,
247                 int argc, const char ** argv, int nongit, const char *prefix)
248 {
249         int i;
250         for (i = 1; i < argc; i++)
251                 if (argv[i][0] != '-' || argv[i][1] == '\0')
252                         break;
253                 else if (!strcmp(argv[i], "--")) {
254                         i++;
255                         break;
256                 } else if (i < argc - 3 && !strcmp(argv[i], "--no-index")) {
257                         i = argc - 3;
258                         revs->diffopt.exit_with_status = 1;
259                         break;
260                 }
261         if (argc != i + 2 || (!is_outside_repo(argv[i + 1], nongit, prefix) &&
262                                 !is_outside_repo(argv[i], nongit, prefix)))
263                 return -1;
264
265         diff_setup(&revs->diffopt);
266         for (i = 1; i < argc - 2; )
267                 if (!strcmp(argv[i], "--no-index"))
268                         i++;
269                 else {
270                         int j = diff_opt_parse(&revs->diffopt,
271                                         argv + i, argc - i);
272                         if (!j)
273                                 die("invalid diff option/value: %s", argv[i]);
274                         i += j;
275                 }
276
277         if (prefix) {
278                 int len = strlen(prefix);
279
280                 revs->diffopt.paths = xcalloc(2, sizeof(char*));
281                 for (i = 0; i < 2; i++) {
282                         const char *p = argv[argc - 2 + i];
283                         /*
284                          * stdin should be spelled as '-'; if you have
285                          * path that is '-', spell it as ./-.
286                          */
287                         p = (strcmp(p, "-")
288                              ? xstrdup(prefix_filename(prefix, len, p))
289                              : p);
290                         revs->diffopt.paths[i] = p;
291                 }
292         }
293         else
294                 revs->diffopt.paths = argv + argc - 2;
295         revs->diffopt.nr_paths = 2;
296         revs->max_count = -2;
297         return 0;
298 }
299
300 int run_diff_files_cmd(struct rev_info *revs, int argc, const char **argv)
301 {
302         int silent_on_removed;
303
304         if (handle_diff_files_args(revs, argc, argv, &silent_on_removed))
305                 return -1;
306
307         if (revs->max_count == -2) {
308                 if (revs->diffopt.nr_paths != 2)
309                         return error("need two files/directories with --no-index");
310                 if (queue_diff(&revs->diffopt, revs->diffopt.paths[0],
311                                 revs->diffopt.paths[1]))
312                         return -1;
313                 diffcore_std(&revs->diffopt);
314                 diff_flush(&revs->diffopt);
315                 /*
316                  * The return code for --no-index imitates diff(1):
317                  * 0 = no changes, 1 = changes, else error
318                  */
319                 return revs->diffopt.found_changes;
320         }
321
322         if (read_cache() < 0) {
323                 perror("read_cache");
324                 return -1;
325         }
326         return run_diff_files(revs, silent_on_removed);
327 }
328
329 int run_diff_files(struct rev_info *revs, int silent_on_removed)
330 {
331         int entries, i;
332         int diff_unmerged_stage = revs->max_count;
333
334         if (diff_unmerged_stage < 0)
335                 diff_unmerged_stage = 2;
336         entries = active_nr;
337         for (i = 0; i < entries; i++) {
338                 struct stat st;
339                 unsigned int oldmode, newmode;
340                 struct cache_entry *ce = active_cache[i];
341                 int changed;
342
343                 if (revs->diffopt.quiet && revs->diffopt.has_changes)
344                         break;
345
346                 if (!ce_path_match(ce, revs->prune_data))
347                         continue;
348
349                 if (ce_stage(ce)) {
350                         struct combine_diff_path *dpath;
351                         int num_compare_stages = 0;
352                         size_t path_len;
353
354                         path_len = ce_namelen(ce);
355
356                         dpath = xmalloc(combine_diff_path_size(5, path_len));
357                         dpath->path = (char *) &(dpath->parent[5]);
358
359                         dpath->next = NULL;
360                         dpath->len = path_len;
361                         memcpy(dpath->path, ce->name, path_len);
362                         dpath->path[path_len] = '\0';
363                         hashclr(dpath->sha1);
364                         memset(&(dpath->parent[0]), 0,
365                                sizeof(struct combine_diff_parent)*5);
366
367                         if (lstat(ce->name, &st) < 0) {
368                                 if (errno != ENOENT && errno != ENOTDIR) {
369                                         perror(ce->name);
370                                         continue;
371                                 }
372                                 if (silent_on_removed)
373                                         continue;
374                         }
375                         else
376                                 dpath->mode = canon_mode(st.st_mode);
377
378                         while (i < entries) {
379                                 struct cache_entry *nce = active_cache[i];
380                                 int stage;
381
382                                 if (strcmp(ce->name, nce->name))
383                                         break;
384
385                                 /* Stage #2 (ours) is the first parent,
386                                  * stage #3 (theirs) is the second.
387                                  */
388                                 stage = ce_stage(nce);
389                                 if (2 <= stage) {
390                                         int mode = ntohl(nce->ce_mode);
391                                         num_compare_stages++;
392                                         hashcpy(dpath->parent[stage-2].sha1, nce->sha1);
393                                         dpath->parent[stage-2].mode =
394                                                 canon_mode(mode);
395                                         dpath->parent[stage-2].status =
396                                                 DIFF_STATUS_MODIFIED;
397                                 }
398
399                                 /* diff against the proper unmerged stage */
400                                 if (stage == diff_unmerged_stage)
401                                         ce = nce;
402                                 i++;
403                         }
404                         /*
405                          * Compensate for loop update
406                          */
407                         i--;
408
409                         if (revs->combine_merges && num_compare_stages == 2) {
410                                 show_combined_diff(dpath, 2,
411                                                    revs->dense_combined_merges,
412                                                    revs);
413                                 free(dpath);
414                                 continue;
415                         }
416                         free(dpath);
417                         dpath = NULL;
418
419                         /*
420                          * Show the diff for the 'ce' if we found the one
421                          * from the desired stage.
422                          */
423                         diff_unmerge(&revs->diffopt, ce->name, 0, null_sha1);
424                         if (ce_stage(ce) != diff_unmerged_stage)
425                                 continue;
426                 }
427
428                 if (lstat(ce->name, &st) < 0) {
429                         if (errno != ENOENT && errno != ENOTDIR) {
430                                 perror(ce->name);
431                                 continue;
432                         }
433                         if (silent_on_removed)
434                                 continue;
435                         diff_addremove(&revs->diffopt, '-', ntohl(ce->ce_mode),
436                                        ce->sha1, ce->name, NULL);
437                         continue;
438                 }
439                 changed = ce_match_stat(ce, &st, 0);
440                 if (!changed && !revs->diffopt.find_copies_harder)
441                         continue;
442                 oldmode = ntohl(ce->ce_mode);
443
444                 newmode = canon_mode(st.st_mode);
445                 if (!trust_executable_bit &&
446                     S_ISREG(newmode) && S_ISREG(oldmode) &&
447                     ((newmode ^ oldmode) == 0111))
448                         newmode = oldmode;
449                 else if (!has_symlinks &&
450                     S_ISREG(newmode) && S_ISLNK(oldmode))
451                         newmode = oldmode;
452                 diff_change(&revs->diffopt, oldmode, newmode,
453                             ce->sha1, (changed ? null_sha1 : ce->sha1),
454                             ce->name, NULL);
455
456         }
457         diffcore_std(&revs->diffopt);
458         diff_flush(&revs->diffopt);
459         return 0;
460 }
461
462 /*
463  * diff-index
464  */
465
466 /* A file entry went away or appeared */
467 static void diff_index_show_file(struct rev_info *revs,
468                                  const char *prefix,
469                                  struct cache_entry *ce,
470                                  unsigned char *sha1, unsigned int mode)
471 {
472         diff_addremove(&revs->diffopt, prefix[0], ntohl(mode),
473                        sha1, ce->name, NULL);
474 }
475
476 static int get_stat_data(struct cache_entry *ce,
477                          unsigned char **sha1p,
478                          unsigned int *modep,
479                          int cached, int match_missing)
480 {
481         unsigned char *sha1 = ce->sha1;
482         unsigned int mode = ce->ce_mode;
483
484         if (!cached) {
485                 static unsigned char no_sha1[20];
486                 int changed;
487                 struct stat st;
488                 if (lstat(ce->name, &st) < 0) {
489                         if (errno == ENOENT && match_missing) {
490                                 *sha1p = sha1;
491                                 *modep = mode;
492                                 return 0;
493                         }
494                         return -1;
495                 }
496                 changed = ce_match_stat(ce, &st, 0);
497                 if (changed) {
498                         mode = ce_mode_from_stat(ce, st.st_mode);
499                         sha1 = no_sha1;
500                 }
501         }
502
503         *sha1p = sha1;
504         *modep = mode;
505         return 0;
506 }
507
508 static void show_new_file(struct rev_info *revs,
509                           struct cache_entry *new,
510                           int cached, int match_missing)
511 {
512         unsigned char *sha1;
513         unsigned int mode;
514
515         /* New file in the index: it might actually be different in
516          * the working copy.
517          */
518         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0)
519                 return;
520
521         diff_index_show_file(revs, "+", new, sha1, mode);
522 }
523
524 static int show_modified(struct rev_info *revs,
525                          struct cache_entry *old,
526                          struct cache_entry *new,
527                          int report_missing,
528                          int cached, int match_missing)
529 {
530         unsigned int mode, oldmode;
531         unsigned char *sha1;
532
533         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0) {
534                 if (report_missing)
535                         diff_index_show_file(revs, "-", old,
536                                              old->sha1, old->ce_mode);
537                 return -1;
538         }
539
540         if (revs->combine_merges && !cached &&
541             (hashcmp(sha1, old->sha1) || hashcmp(old->sha1, new->sha1))) {
542                 struct combine_diff_path *p;
543                 int pathlen = ce_namelen(new);
544
545                 p = xmalloc(combine_diff_path_size(2, pathlen));
546                 p->path = (char *) &p->parent[2];
547                 p->next = NULL;
548                 p->len = pathlen;
549                 memcpy(p->path, new->name, pathlen);
550                 p->path[pathlen] = 0;
551                 p->mode = ntohl(mode);
552                 hashclr(p->sha1);
553                 memset(p->parent, 0, 2 * sizeof(struct combine_diff_parent));
554                 p->parent[0].status = DIFF_STATUS_MODIFIED;
555                 p->parent[0].mode = ntohl(new->ce_mode);
556                 hashcpy(p->parent[0].sha1, new->sha1);
557                 p->parent[1].status = DIFF_STATUS_MODIFIED;
558                 p->parent[1].mode = ntohl(old->ce_mode);
559                 hashcpy(p->parent[1].sha1, old->sha1);
560                 show_combined_diff(p, 2, revs->dense_combined_merges, revs);
561                 free(p);
562                 return 0;
563         }
564
565         oldmode = old->ce_mode;
566         if (mode == oldmode && !hashcmp(sha1, old->sha1) &&
567             !revs->diffopt.find_copies_harder)
568                 return 0;
569
570         mode = ntohl(mode);
571         oldmode = ntohl(oldmode);
572
573         diff_change(&revs->diffopt, oldmode, mode,
574                     old->sha1, sha1, old->name, NULL);
575         return 0;
576 }
577
578 static int diff_cache(struct rev_info *revs,
579                       struct cache_entry **ac, int entries,
580                       const char **pathspec,
581                       int cached, int match_missing)
582 {
583         while (entries) {
584                 struct cache_entry *ce = *ac;
585                 int same = (entries > 1) && ce_same_name(ce, ac[1]);
586
587                 if (revs->diffopt.quiet && revs->diffopt.has_changes)
588                         break;
589
590                 if (!ce_path_match(ce, pathspec))
591                         goto skip_entry;
592
593                 switch (ce_stage(ce)) {
594                 case 0:
595                         /* No stage 1 entry? That means it's a new file */
596                         if (!same) {
597                                 show_new_file(revs, ce, cached, match_missing);
598                                 break;
599                         }
600                         /* Show difference between old and new */
601                         show_modified(revs, ac[1], ce, 1,
602                                       cached, match_missing);
603                         break;
604                 case 1:
605                         /* No stage 3 (merge) entry?
606                          * That means it's been deleted.
607                          */
608                         if (!same) {
609                                 diff_index_show_file(revs, "-", ce,
610                                                      ce->sha1, ce->ce_mode);
611                                 break;
612                         }
613                         /* We come here with ce pointing at stage 1
614                          * (original tree) and ac[1] pointing at stage
615                          * 3 (unmerged).  show-modified with
616                          * report-missing set to false does not say the
617                          * file is deleted but reports true if work
618                          * tree does not have it, in which case we
619                          * fall through to report the unmerged state.
620                          * Otherwise, we show the differences between
621                          * the original tree and the work tree.
622                          */
623                         if (!cached &&
624                             !show_modified(revs, ce, ac[1], 0,
625                                            cached, match_missing))
626                                 break;
627                         diff_unmerge(&revs->diffopt, ce->name,
628                                      ntohl(ce->ce_mode), ce->sha1);
629                         break;
630                 case 3:
631                         diff_unmerge(&revs->diffopt, ce->name,
632                                      0, null_sha1);
633                         break;
634
635                 default:
636                         die("impossible cache entry stage");
637                 }
638
639 skip_entry:
640                 /*
641                  * Ignore all the different stages for this file,
642                  * we've handled the relevant cases now.
643                  */
644                 do {
645                         ac++;
646                         entries--;
647                 } while (entries && ce_same_name(ce, ac[0]));
648         }
649         return 0;
650 }
651
652 /*
653  * This turns all merge entries into "stage 3". That guarantees that
654  * when we read in the new tree (into "stage 1"), we won't lose sight
655  * of the fact that we had unmerged entries.
656  */
657 static void mark_merge_entries(void)
658 {
659         int i;
660         for (i = 0; i < active_nr; i++) {
661                 struct cache_entry *ce = active_cache[i];
662                 if (!ce_stage(ce))
663                         continue;
664                 ce->ce_flags |= htons(CE_STAGEMASK);
665         }
666 }
667
668 int run_diff_index(struct rev_info *revs, int cached)
669 {
670         int ret;
671         struct object *ent;
672         struct tree *tree;
673         const char *tree_name;
674         int match_missing = 0;
675
676         /* 
677          * Backward compatibility wart - "diff-index -m" does
678          * not mean "do not ignore merges", but totally different.
679          */
680         if (!revs->ignore_merges)
681                 match_missing = 1;
682
683         mark_merge_entries();
684
685         ent = revs->pending.objects[0].item;
686         tree_name = revs->pending.objects[0].name;
687         tree = parse_tree_indirect(ent->sha1);
688         if (!tree)
689                 return error("bad tree object %s", tree_name);
690         if (read_tree(tree, 1, revs->prune_data))
691                 return error("unable to read tree object %s", tree_name);
692         ret = diff_cache(revs, active_cache, active_nr, revs->prune_data,
693                          cached, match_missing);
694         diffcore_std(&revs->diffopt);
695         diff_flush(&revs->diffopt);
696         return ret;
697 }
698
699 int do_diff_cache(const unsigned char *tree_sha1, struct diff_options *opt)
700 {
701         struct tree *tree;
702         struct rev_info revs;
703         int i;
704         struct cache_entry **dst;
705         struct cache_entry *last = NULL;
706
707         /*
708          * This is used by git-blame to run diff-cache internally;
709          * it potentially needs to repeatedly run this, so we will
710          * start by removing the higher order entries the last round
711          * left behind.
712          */
713         dst = active_cache;
714         for (i = 0; i < active_nr; i++) {
715                 struct cache_entry *ce = active_cache[i];
716                 if (ce_stage(ce)) {
717                         if (last && !strcmp(ce->name, last->name))
718                                 continue;
719                         cache_tree_invalidate_path(active_cache_tree,
720                                                    ce->name);
721                         last = ce;
722                         ce->ce_mode = 0;
723                         ce->ce_flags &= ~htons(CE_STAGEMASK);
724                 }
725                 *dst++ = ce;
726         }
727         active_nr = dst - active_cache;
728
729         init_revisions(&revs, NULL);
730         revs.prune_data = opt->paths;
731         tree = parse_tree_indirect(tree_sha1);
732         if (!tree)
733                 die("bad tree object %s", sha1_to_hex(tree_sha1));
734         if (read_tree(tree, 1, opt->paths))
735                 return error("unable to read tree %s", sha1_to_hex(tree_sha1));
736         return diff_cache(&revs, active_cache, active_nr, revs.prune_data,
737                           1, 0);
738 }